As the sole output from the cerebellar cortex, Purkinje cells are responsible for processing information from diverse brain regions and delivering this information to the cells of the cerebellar nucleus. Although signal processing is known to occur in the dendrites and the soma, little is known about the processing that may also occur in the axons of Purkinje cells. Specifically, we are interested in the pattern of axonal action potentials that result from the massive depolarization observed in Purkinje cell somata and dendrites during stimulation of climbing fibers (i.e. complex spike). Moreover, high-frequency firing and extensive branching may reduce the reliability of transmission in axons. Using electrophysiological and imaging techniques, we propose to determine the transfer function of Purkinje cell axons in periods of high-frequency and burst firing. We also propose to test the reliability of action potential propagation throughout the highly ramifying collateral axons and terminal projections to the deep cerebellar nucleus.